A complete understanding the most powerful sense that we possess is just still in its infancy – our sense of smell. While scientists have made significant progress in uncovering the complexities of our olfactory system in recent decades, there is still so much we do not know.
The main things we do know are divided into 3 categories:
- How the olfactory system ties into our mind and body
- How scents affect our emotions
- How it mechanically works – including nuances like nose blindness and irritation
This blog addresses the mechanics of “Nose Blindness.” Nose Blindness is a natural occurrence in our olfactory system. It occurs when you initially smell something, and although that scent remains present in the air around us, we stop registering that smell until it either goes away and comes back or increases in intensity.
The big question is why?
“The idea behind nose blindness is that the olfactory system is designed to detect changes in our environment,” says olfactory scientist and experimental psychologist Pam Dalton, PhD, MPH, who conducts research on nose blindness and scent at the Monell Chemical Senses Lab in Philadelphia. “When a chemical is present for a long period of time—and by long, it could be a minute to five minutes to an hour—the receptors in the nose stop responding to it because it’s no longer providing new information.” 1
It is also about survival, and the primitive nature of the olfactory system. It is first and foremost a defensive alert mechanism that invokes an individual’s flight or fight instincts.
“If we have survived breathing in an environment for a few minutes while smelling an odor and nothing bad has happened, we don’t really need to pay attention to that smell anymore—so we stop being able to detect it.” —Pam Dalton, PhD, MPH1
In addition to Nose Blindness, another nuance is Olfactory Irritation. A study was performed in a spa setting with the scent of bergamot. Researchers in Taiwan set up an experiment that was meant to mimic the conditions at a typical spa. They used a vaporizer to fill the air in a closed room with tiny droplets of essential oil of bergamot. Bergamot oil comes from a citrus fruit. It’s a common ingredient in perfumes, massage oils, and aromatherapy.
Researchers then asked 100 healthy, young spa workers to stay in the room for two hours on each of three separate visits. Researchers kept tabs on the workers heart rates and blood pressures every 15 minutes while they were breathing the vaporized oil. In the first hour that the study volunteers stayed in the room, their heart rates and blood pressures dropped slightly. However, after 75 continuous minutes of exposure, the trend reversed. Worker’s heart rates and blood pressures began to climb. The olfactory system was irritated after an hour with the continued presence of a scent.
Nose Blindness and Olfactory Irritation nuances are just two reasons why it is why it is important to use the most advanced technology to deliver scent in the home. Dry-air systems with cadenced release mechanisms can deliver scent in short bursts and do not cause nose blindness or irritation. It’s somewhat ironic that Irritation is the opposite of why people use aromatherapy in home in the first place